In collaboration with Oxford University, a small Phase 2a challenge study was conducted where volunteers were immunized with AMA1-C1/Alhydrogel+CPG 7909, followed by a challenge dose of erythrocytes infected with malaria parasites. A significant correlation was observed between parasite multiplication rate and both vaccine-induced growth-inhibitory activity and AMA1 antibody titers. However, this did not translate to an overall observable clinically relevant vaccine effect in these volunteers. Currently the collaboration with Oxford University continues in a prime-boost study where volunteers are primed with viral-vectored AMA1 vaccines followed by a booster dose of AMA1-C1/Alhydrogel+CPG 7909. The AMA1-C1/Aldhyrgel+CPG7909 is also being tested in combination with another merozoite stage antigen in an Aotus challenge model.